Re: [PATCH 1/6] mci: use struct cid

[Sascha Hauer <s.hauer@pengutronix.de>]

On Mon, Mar 17, 2025 at 12:41:22PM +0300, Alexander Shiyan wrote:
> Hello.
> 
> > Linux has a struct mmc_cid where the CID data is parsed into whereas
> > in barebox we call the UNSTUFF_BITS macro whenever we need a field
> > from the CID data. Do it like Linux and parse the CID data into the
> > same struct. While at it convert the UNSTUFF_BITS macro into a
> > unstuff_bits static inline function.
> ...
> > diff --git a/drivers/mci/mci-core.c b/drivers/mci/mci-core.c
> > index 7ec2643b8d..34ea775813 100644
> > --- a/drivers/mci/mci-core.c
> > +++ b/drivers/mci/mci-core.c
> > @@ -26,19 +26,19 @@
> >
> >  #define MAX_BUFFER_NUMBER 0xffffffff
> >
> > -#define UNSTUFF_BITS(resp,start,size)                                  \
> > -       ({                                                              \
> > -               const int __size = size;                                \
> > -               const u32 __mask = (__size < 32 ? 1 << __size : 0) - 1; \
> > -               const int __off = 3 - ((start) / 32);                   \
> > -               const int __shft = (start) & 31;                        \
> > -               u32 __res;                                              \
> > -                                                                       \
> > -               __res = resp[__off] >> __shft;                          \
> > -               if (__size + __shft > 32)                               \
> > -                       __res |= resp[__off-1] << ((32 - __shft) % 32); \
> > -               __res & __mask;                                         \
> > -       })
> > +static inline u32 unstuff_bits(const u32 *resp, int start, int size)
> > +{
> > +       const int __size = size;
> > +       const u32 __mask = (__size < 32 ? 1 << __size : 0) - 1;
> > +       const int __off = 3 - (start / 32);
> > +       const int __shft = start & 31;
> > +       u32 __res = resp[__off] >> __shft;
> > +
> > +       if (__size + __shft > 32)
> > +               __res |= resp[__off - 1] << ((32 - __shft) % 32);
> > +
> > +       return __res & __mask;
> > +}
> 
> For board specific code where the eMMC ID is used as a unique identifier,
> it would be useful to have this function in the header.

Wouldn't you rather use something like getenv("mmc0.cid_psn") then?

We could also introduce some mmc helper function for convenience.

Sascha

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